Fix misoptimization of 'is' test

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 #define RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 3085 matching lines @@
 
   virtual Condition EmitComparisonCode(FlowGraphCompiler* compiler,
                                        BranchLabels labels);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestSmiInstr);
 };
 
 
 // Checks the input value cid against cids stored in a table and returns either
-// a result or deoptimizes.
+// a result or deoptimizes.  If the cid is not in the list and there is a deopt
+// id, then the instruction deoptimizes.  If there is no deopt id, all the
+// results must be the same (all true or all false) and the instruction returns
+// the opposite for cids not on the list.  The first element in the table must
+// always be the result for the Smi class-id and is allowed to differ from the
+// other results even in the no-deopt case.
 class TestCidsInstr : public TemplateComparison<1, NoThrow, Pure> {
  public:
   TestCidsInstr(TokenPosition token_pos,
                 Token::Kind kind,
                 Value* value,
                 const ZoneGrowableArray<intptr_t>& cid_results,
-                intptr_t deopt_id)
-      : TemplateComparison(token_pos, kind, deopt_id),
-        cid_results_(cid_results),
-        licm_hoisted_(false) {
-    ASSERT((kind == Token::kIS) || (kind == Token::kISNOT));
-    SetInputAt(0, value);
-    set_operation_cid(kObjectCid);
-  }
+                intptr_t deopt_id);
 
   const ZoneGrowableArray<intptr_t>& cid_results() const {
     return cid_results_;
   }
 
   DECLARE_INSTRUCTION(TestCids);
 
   virtual ComparisonInstr* CopyWithNewOperands(Value* left, Value* right);
 
   virtual CompileType ComputeType() const;
@@ skipping 5090 matching lines @@
   LocationSummary* Name::MakeLocationSummary(Zone* zone, bool opt) const {     \
     UNIMPLEMENTED();                                                           \
     return NULL;                                                               \
   }                                                                            \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_